by Natalie Banks - Chief Adviser, Apex Harmony

When it comes to SMART drum lines, not many people are aware of what exactly is so clever about them. Drum lines have had extremely controversial use in Australia and South Africa, where static baited hooks indiscriminately catch anything that takes the bait, but what is so smart about these new types of drum lines and why are some conservation groups in support of their use?

The word smart when used in accordance with drum lines is actually an abbreviation that stands for Shark-Management-Alert-in-Real-Time (SMART). Effectively this means a satellite-linked communications unit, equipped in some cases with GPS, underwater cameras and sensors attached to a trace and baited hook so that when a shark is hooked, the pressure on the line triggers the communications unit to send an alert to authorities regarding the presence of an animal on the line. The technology has enabled Governments and Government contractors to streamline the monitoring process of traditional drum lines.

SMART drum lines were initially used in the French island of La Reunion in January 2014. The aim was to reduce unnecessary mortality of some marine animals, while undertaking a cull of bull and tiger sharks of 1.5m and 2.5m in size respectfully, to protect ocean users and to test for Ciguatera poisoning. Interestingly, one of the engineers behind the SMART drum line technology, David Guyomard believes that the tiger sharks are culled because a balance exists between the bull and tiger sharks. After killing too many bull sharks with the netting system in South Africa, the KwaZulu Natal Shark Board realized that tiger sharks were moving in.

The results of the SMART drum line captures in La Reunion are not easily found publicly, but a report by Cardno in conjunction with Daryl McPhee from Bond University in October 2015 found that while the catch numbers reported were low, there was a 50% mortality rate of some shark species, particularly the Hammerhead. The positive news however, was that in all instances, the survival rate of sharks caught on SMART drum lines was markedly increased compared to traditional drum lines used in Queensland. In the past five months of SMART drum line use in northern New South Wales, 31 targeted sharks have been caught, with one death of a white shark recorded recently.

3.1m White shark caught on SMART Drumline at South Wall, Ballina, 30 April, 2017. Tagged and released 1km offshore. Credit: Department of Primary Industries

Reducing Shark Bites?

SMART drum lines are primarily an advanced fishing and research tool, used to better understand the movements and distribution of sharks. There have been no independent reviews undertaken on SMART drum lines regarding their ability to reduce shark bites. La Reunion started using SMART drum lines regularly in August 2015 where they would catch and kill bull and tiger sharks. Given that La Reunion started culling sharks in 2011 and that there have been 21 shark bites, nine fatal during the past six years, compared to four shark bites and one fatality in the six years from 2005 to 2011, it is evident that culling isn’t working to reduce shark bites.

BUT Australia is taking a different tactic when it comes to the use of SMART drum lines. Instead of killing the sharks after being caught, they are tagging, relocating and then releasing them. This is a similar practice to a program in Recife, Brazil that took place between 2004 and 2011, where sharks were caught on drum lines with a circle hook, (allowing the shark to swim and therefore oxygenate) and tagged before being relocated. The shark relocation program was in operation for 73 months and was inactive for 23 months due to funding shortfalls. Therefore, researchers were able to compare the frequency of shark attacks while the program was active to the months it was on hold. While the program was operational, Recife saw an impressive 97% reduction in the monthly shark attack rate.

But Alison Kock, a marine biologist and the research manager at Shark Spotters in Cape Town, South Africa has advised that there have been mixed results from Recife, Brazil program. In December 2015, Kock advised Australian Broadcasting Corporation “Fact Check”;

"The data shows a reduced mortality rate using this method and a decline in shark attacks at Recife itself, but the data also shows an increase in shark attacks at an adjacent beach, leaving one wondering whether they have simply moved the problem elsewhere."

Recent headlines regarding Recife claim that “no-one goes in the water” anymore. Interestingly, it is Recife's Port Suape that many people see as the biggest cause of the recent attacks. Located 20km south of Boa Viagem Beach, where most of the attacks have occurred, the port has been the cause of much disturbance for marine life along the coast and the nearby estuaries. During construction, workers dredged these estuaries and built long docks that spanned out into the ocean. According to the BBC, this interrupted the breeding and hunting habitats of bull sharks, forcing them to move closer to the Recife coast line.

Construction of Port Suape began in the late 1970s, but it was not until 1992 that it began to attract significant shipping traffic. Before 1992, Recife had no more shark attacks than any other beach in Brazil, but this changed quite dramatically over the next few decades. Just like in La Reunion in the Indian Ocean, when a team of free divers advised the French Government in 2011 that the only sharks they could find were all in one area, orbiting a heap of trash on the seafloor near the Boucan Canot marina and Saint Gilles harbor, Port Suape’s increasing ship traffic and the garbage being tossed from boats could be attracting sharks to the area.

When looking at Global Shark Attack reports, it is evident to see the increase of shark encounters at Boa Viagem Beach since 1992, but if we look at the shark encounters in the State of Pernambuco of which Recife is the capital in the seven years prior, the seven years during and the four years after the shark relocation program, the results illustrate that there has been some reduction in shark bites during and after the shark relocation program, albeit with a higher than average shark bite fatality for the region. Between 1996 to 2003 inclusive, there were 23 shark encounters with 10 shark bite fatalities. During the trial, between 2004 to 2011 inclusive, there were 17 shark encounters with six shark bite fatalities and between 2012 to 2016 there was been four shark encounters with three shark bite fatalities.

It cannot be said with certainty that using smart drum lines to relocate sharks will prevent shark attacks in northern New South Wales, but equally their effectiveness cannot as yet be ruled out.

SMART drum lines used in northern New South Wales

Additional Concerns

Additional concerns with the use of 35 SMART drum lines in northern New South Wales is that they can only be effective in reducing mortality if sea conditions do not prevent a contractor immediately attending the drum line to deal with the captured animal. There may also be practical challenges of requiring a contractor to be on standby and be able to rapidly deploy to tend the drum line when a capture occurs. Already, contractors are having difficulties maintaining shark nets due to local conditions and so therefore I remain optimistically cautious about their continual use.

This is definitely one to watch and I commend the New South Wales Government on recognising that the shark net trial was not a suitable solution for the northern New South Wales coastline. Whether the use of SMART drum lines, mixed with a tagging and relocation program is successful in reducing shark encounters in northern New South Wales is yet to be seen. But in the meantime, it is highly recommended that shark spotting exercises are introduced at suitable beaches in Northern New South Wales and that beach users undertake increased personal responsibility like checking the NSW Shark Smart applications for shark sightings and purchasing proven shark deterrents and life-saving aquatic trauma kits before entering the ocean, in an area that is currently undergoing an increase in shark activity.